After being reveiwed by Governor Hastings on May 3, 1898, all of the officers and men enlisted for the federal service. Although one officers and thirty enlisted men were rejected for medical reason, one hundred and fifty additional recruits subsequently arrived from Pittsburgh on May 9. Two days later, companies B, C, F and G were mustered into the federal service, followed by companies A, D and H the following day, and Company E and the Field and Staff on May 13th. At the time of mustering in, the regiment consisted of thirty-four officers and 604 enlisted men. The regiment remained at Camp Hastings until early June. On June 4, Company F was ordered to Alliance, Ohio, to guard the Morgan Iron Company facility, reporting to the commanding officer of the Army's "Department of the Lakes" at Chicago, Illinois. On June 7th, the remainder of the regiment, serving with the Army's"Department of the East" was ordered to Battery Point, near Delaware City, Delaware, on the Delaware Bay. The force arrived at this location on June 17, reinforced by seventy-one additional recruits that had arrived two days earlier. Shortly afterwards, on June 23, companies E, H and I were ordered to Fort Brady, Michigan. Company D was ordered to Fort Wayne, located at Detroit to guard locks on the Sault Ste Marie Canal.
The remainder of the regiment, after spending only a few days at Battery Point, was ordered on August 22 to return to Camp Meade, being created near Middletown, Pennsylvania. Here the regiment was rejoined by Company D from Detroit on August 23, and by Company F from Ohio on August 24. At Camp Meade, the regiment was assigned to the 2nd Army Corps.
On September 2, 1898, the regiment was ordered back to Pittsburgh. In Pittsburgh, the regiment was granted a thirty day furlough, which was later extended to forty days. On October 22, the regiment was mustered out of service. At the time of mustering out, the regiment of thirty-four officers and 837 enlisted men. During its term of service, the regiment had one enlisted man die of disease, and two men desert. In addition, ten men were discharged on disability.
Statistical Exhibit of Strength of Volunteer Forces Called into Service During the War with Spain; with Losses from All Causes. (Washington: Government Printing Office, 1899).
Stewart, Adj. Gen. Thomas J., Record of the Pennsylvania Vounteers. (Harrisburg: William Stanley Ray, 1901), 529.